Field of the Invention
The present invention relates to a magnetic recording and reproducing apparatus and a magnetic head used for the apparatus. More, particularly, it relates to a magnetic recording and reproducing apparatus capable of recording data with a high density and a magnetic head having a slider capable of flying with a flying height, which is used for the magnetic recording and reproducing apparatus.
Discussion of Background
It has been known heretofore that a magnetic recording and reproducing apparatus with a flying type magnetic head capable of flying with a microscopic gap from a magnetic recording medium by a minute air bearing which is formed due to the dynamic pressure caused when the magnetic recording medium is moved. Some conventional flying type magnetic heads are disclosed in, for example, Japanese Examined Patent Publication Nos. 21329/1983, 28650/1983 and so forth. The basic construction described therein is such that reading/writing elements are attached to the air discharge end of a slider having a flying plane on its one side opposed to a magnetic recording medium.
FIG. 15 is a perspective view of such exemplary conventional magnetic head, wherein there are shown a slider 1 composed of a ceramic material or the like, and reading/writing elements 2. The slider 1 has, on its one surface opposed to a magnetic recording medium, two rails 101, 102 which are spaced apart from each other and have flying planes 103, 104 defined with a high flatness. On the flying planes 103, 104, tapered portions 103a, 104a are formed at the inflow ends thereof relative to an air stream flowing in the direction indicated by an arrow mark a in combination with the magnetic recording medium. The reading/writing elements 2 are thin-layer elements produced by the same process as in the IC manufacture technology and attached to the air discharge end on the reverse side with respect to the tapered portions 103a, 104a.
In the use for a magnetic recording and reproducing apparatus, the magnetic head is secured to the fore end of an unshown gimbal support device, and the flying planes 103, 104 of the slider 1 are brought into elastic contact with the surface of the magnetic disk. And the magnetic head held in such a state is driven in the so-called contact start-stop mode. When the magnetic disk is kept still, the flying planes 103, 104 of the slider 1 are pressed elastically against the dick surface. But upon start of rotation of the magnetic disk, as illustrated in FIG. 16, a lifting dynamic pressure is exerted on the flying planes 103, 104 of the slider 1 including the tapered portions 103a, 104a , so that the magnetic head is caused to fly by a flying height q based on the balance between such dynamic pressure and the resilient pressure P of the gimbal spring.
In this case, operations were carried out at a region where the flying height g was about 0.3 .mu.m.
In the conventional magnetic recording and reproducing apparatus of this kind, the flying height g of the magnetic head should be small as possible to realize high density recording. However, there has been a problem that the withstanding properties of the magnetic disk and the magnetic head are greatly decreased when the flying height is to be reduced.
FIG. 14 is a diagram showing data in relation of revolution number to frictional coefficient in a conventional magnetic recording and reproducing apparatus. A magnetic head used for obtaining the data is of a type having rails as shown in FIGS. 15 and 16 in which the length in the direction of an air stream of the head is 3.2 mm and the width is 2.6 mm. A load of 7.0 g is exerted to the magnetic disk by means of a head supporting device. A lubricant having a concentration of 0.1% is applied to the surface of the magnetic disk.
As is apparent from the data, the frictional coefficient gradually decreases as the revolution number is increased. On the contrary, the frictional coefficient gradually increases as the revolution number is decreased. Accordingly, when the apparatus is driven by the contact start-stop mode, an unnegligible large resistance of friction occurs for a fairly long time between the magnetic disk and the magnetic head at the time of starting or stopping, whereby there easily takes place a damage by crushing and so on, and the durability is decreased.
On the other hand, when the surface properties of the magnetic disk are increased to thereby improve the durability, the magnetic head is apt to be strongly stuck to the surface of the magnetic disk due to influence of moisture or water component in air; so that it becomes impossible to start. Therefore in the conventional magnetic recording and reproducing apparatus, there was a limit in an attempt to further reduce the flying height.